


hold your breath and count to four

by SkyGem



Category: Katekyou Hitman Reborn!, 僕のヒーローアカデミア | Boku no Hero Academia | My Hero Academia
Genre: BAMF Izuku, BAMF Tsuna, Gen, bakugou and izuku friendship!!!, hero and villain (technically) friendships!!!, international friendships, look i just wanted my two sons to meet, non toxic bakugou, redeemed bakugou, this is all just self indulgent bs, tsuna being hecka unnerving, tsuna is still going to destroy the vongola from the inside out, uhhhhh i don't know how to tag this
Language: English
Status: In-Progress
Published: 2020-08-24
Updated: 2020-08-29
Packaged: 2021-03-07 02:33:53
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 3,687
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/26079562
Author URL: https://archiveofourown.org/users/SkyGem/pseuds/SkyGem
Summary: The first time Izuku meets the young boss of Italy's Vongola Family, he doesn't have any idea who the young man is.
Relationships: Midoriya Izuku & Sawada Tsunayoshi
Comments: 50
Kudos: 556





	1. Chapter 1

**Author's Note:**

> Look, Imma be real with you chief....this is just an excuse for me to write whatever I want. This is gonna be really short, just a couple of chapters, I just thought it would be cool to see how the Vongola family would fit into the bnha world.
> 
> Am I ever going to continue my other bnha/khr crossover? Maybe some day.

The first time Izuku meets the young boss of Italy's Vongola Family, he doesn't have any idea who the young man is.

The summer break of his third year at UA is drawing to an end, and he and a couple of his friends are out shopping, taking advantage of their last few days of freedom before their imminent return to Aizawa-sensei's grueling training curriculum.

They're grabbing lunch at a quiet little sushi restaurant when the door slams open, and three bulky men walk in bearing weapons.

Izuku is immediately on high alert.

He darts his eyes around the little dining area, taking note of anyone around them that would need protecting.

They're lucky - the restaurant is mostly empty at this time of the day, and the only other patrons are a young man around their age seated at a table in the corner, and his companion, a young boy with curly black hair and brilliantly green eyes, looking over his shoulder at the newcomers with a lot less fear than he probably should have.

"Nobody make any funny moves, unless you wanna to be full of bullets!" the apparent leader of the villains growls as he approaches the cash register.

His two friends are a step behind him, grinning cockily and aiming their guns at Izuku's group, and the civilians at the other table.

There's only two employees visible behind the counter - one, a young cashier who looks to be barely out of high school and is shaking like a leaf, while the other is the chef, an older man well into his fifties who immediately moves to put his body between the villains and his younger co-worker.

"Now, now, no need for that," the lead villain says with a cackle when he sees the chef move. "Just give us what we want, and nobody needs to get hurt!"

Izuku is still thinking of how they should apprehend the villains with the least amount of risk to the others on the scene, when he's beaten to the punch by a burst of laughter from next to him.

"You guys have _got_ to be the stupidest villains I've ever met," says Shinsou's taunting voice, thick with condescension, and the effect is immediate as all three villains turn their attention on him, their expressions outraged.

"What the _fuck_ did you just-?" 

"You watch what you're saying you-"

"Do you want to die, you-"

The villains all start yelling at the same time, but before any of them can finish their sentences, they immediately cut off and their expressions go blank.

"Now drop your weapon to the ground and put your hands behind your backs."

The villains obey without complaint, their faces still slack as their weapons clatter to the ground at their feet.

There's a moment of stunned silence as they wait for their next orders, a silence which is broken when Izuku and his classmates burst out laughing uproariously.

"I can't believe it worked on _all of them_!" Katsuki says through wheezing laughter.

Uraraka reaches out a hand towards Shinsou for a high five, and the boy just complies with an eye-roll and a pleased little grin.

"Come on, you guys," says Shinsou. "Hurry up and knock them out before something happens to make me lose control of them. I doubt the same trick is going to work a second time."

With a massive effort, Katsuki and Uraraka stop laughing enough to get up and help Shinsou secure the villains, while Izuku approaches the two restaurant employees.

He smiles reassuringly at the two as he reaches into his back pocket for his provisional hero license.

"Are you two alright?" he asks them. "Please don't worry about these guys. My friends and I are all hero students from UA."

The older man, who is still standing protectively in front of his younger co-worker, studies the license Izuku shows him for a few tense seconds, before his shoulders finally relax, and he returns Izuku's smile with a nervous one of his own.

"Thank you so much, young man," he says. "I don't know how I can ever repay you for taking care of things so efficiently."

"Aww, don't worry about it!" says Izuku, waving off his words. "Thanks to Shinsou, we didn't even have to really do anything. And besides, we're just doing our job."

"You guys were so amazing though!" says the cashier, stepping out from behind the chef. "You UA students really are on another level. You guys are even younger than me, but you were so calm even though they were waving those big scary weapons around!"

"Nah, we just got lucky that Shinsou was able to catch them off guard!" says Uraraka, from where she's just finished tying the three villains together.

Izuku turns back to them, and sees Shinsou holding two of their weapons, while Katsuki holds the last one.

"Did you guys check if they have any other weapons hidden on their bodies?" he asks.

"We're not idiots, Deku," Katsuki replies with a huff. "Of course we checked. But these guys really are the stupidest villains in Japan. They don't have anything on them other than their guns."

"Okay great," says Izuku. Then, to the two restaurant employees, he asks, "Would one of you mind please calling the police?"

"O-oh, of course!" the cashier says, before turning to run into the back room to get her cell phone.

No sooner is she gone than Izuku feels a tugging on his shirt, and he turns to see the little black-haired child from before, standing next to him and looking up at him with stars in his eyes.

"Hey, hey mister! You're a hero student, right? What's your name? Your hero name!"

Izuku grins down at the child, feeling a small part of him go mushy at how much the kid reminds him of himself at that age.

"I'm Deku," he says, bowing slightly. "A third year in UA's class 3-A. I hope you weren't too scared, kid."

"Nu uh!" says the kid, shaking his head. "I wasn't scared _at all_! See, my big brother, he's a hero too!"

Izuku's eyebrows shoot up in surprise, and he looks up to see the young boy's companion leaning forward with his chin in one of his hands, watching their interaction with a keen eye and a relaxed smile stretched across his lips. When he sees Izuku looking, he waves a little with his free hand.

He looks perfectly friendly, but Izuku feels a shiver of unease run up his spine. There's something not right about the guy, his gut is telling him, though he can't figure out what it would be.

The young boy is still rambling about his big brother.

"Him and his friends are soooooo strong and I'm going to be just like them when I get older!" the kid goes on, bouncing on the balls of his feet in excitement. "But-but we're from Italy! So Tsuna-nii didn't know if he's allowed to fight, you know? He was going to do it anyways if anything bad happened, or if no heroes came, but then you guys took out the villains so _fast_ and you said that you were all heroes and it was so cool!"

"Really? Well it's a good thing that my friends and I were here to take care of things then! The laws around provisional hero licenses can be pretty complicated if you're not in your own country. Are you and your big brother here on vacation? Your Japanese is very good!"

"That's because we used to live here!" the little boy answers, and he looks inordinately proud of himself for some reason. "My big brother was even raised here! But we had to move back to Italy a few years ago because of the family business. We're here visiting our mama during summer break!"

The little kid keeps rambling right up until the police arrive on the scene, and Izuku makes sure to keep oohing and aahing at the right moments, keeping the little kid entertained as long as he can until he's called away by the officers to answer a few questions about the incident.

By the time everything is over and the villains have been taken away, Izuku expects the little boy to and his big brother to have left the scene, and is surprised to see them waiting for him.

The big brother, Tsuna, approaches him while his friends pack up their things to leave, and Izuku notices for the first time that he's wearing a neatly pressed black suit, which makes him look more mature than his baby face suggests he is.

His messy brown hair is the only thing about him that isn't neatly in place, and Izuku privately thinks that it makes him look a lot less intimidating than he would otherwise.

( _He's had enough PR Management classes with Midnight at this point to realize the effect is probably intentional._ )

The boy smiles, and his eyes crinkle up at the corners, warm and friendly.

"I would like to thank you and your friends for taking care of those villains earlier," the boy says. "And for entertaining my little brother too. I hope he didn't bother you too much - he's just such a big fan of pro heroes."

"No, don't worry about it, really!" Izuku insists. "Your brother is very sweet, and he obviously looks up to you a lot. I hope you two enjoy the rest of your stay in Japan!"

"I appreciate it," Tsuna replies. "Italy is a beautiful country, but after living their for two years now, I still find myself getting rather homesick from time to time. It's good to be back, and to see that we have such promising young heroes to protect our lovely country now that All Might is gone. Please continue to work hard."

"O-of course. Thank you very much!" Izuku replies immediately. 

They bid each other farewell after that, and Izuku watches the two strange young men leave.

They had both been the very definition of friendly, but there was something about them that had made him uneasy.

He almost thinks it's all just in his mind, until he feels a hand on his shoulder, and turns to see the rest of his classmates with their eyes trained on Tsuna's retreating back.

Katsuki's grip tightens on Izuku's shoulder.

"I don't trust that fucker."

**Notes for the Chapter:**

> I hope you guys enjoy this chapter! Please leave a comment below letting me know what you think!
> 
> Next chapter of the soulmates au should be up on like thursday or something. Next chapter of they'll call me freedom is on saturday!
> 
> Check me out on tumblr under the url skygemspeaks!


	2. Chapter 2

Aizawa-sensei is already waiting for them by the time they arrive back at their dorms two hours later, and he does _not_ look happy.

Iida pulls them aside as soon as they walk through the front door to demand what the hell they had gotten up to while they were out, and to warn them that their teacher isn't the least bit happy with them.

Izuku trades worried looks with his friends at the news.

They hadn't seen much of Aizawa since they had settled back into their dorms a couple of days ago - he usually likes to spend the last couple of days before the start of term catching up on his sleep, since he isn't likely to get much more until winter break.

They approach the living room like frightened animals, noting that there's no sound coming from it, which almost never happens at this time of the day. Their classmates must be avoiding it for fear of being pulled into whatever scolding was planned for whichever of their classmates had gotten on Aizawa's bad side.

They find their teacher sitting in one of the armchairs, staring stoically into space.

He doesn't move as they all gingerly take seats in the sofas around him (all of them except for Katsuki, who makes a big show of how totally-not-nervous he is by dropping casually into his seat. The stiffness of his movements betrays him.)

Aizawa waits until they're all seated before looking each of them in the eye in turn, his gaze landing on Izuku last and staying on him the longest, having apparently pinned him as the ringleader.

"What. The hell. Did you brats get yourselves into?" he finally demands, his voice low and dangerous, and Izuku feels a shiver run up his spine.

This is different from Aizawa-sensei's usual scoldings.

He notices for the first time that Aizawa's crossed arms are trembling slightly.

"We were just getting lunch and minding our own business, honest!" Uraraka answers right away. "It's not like we were out looking for trouble or anything! Those villains just happened to-"

"That's not what I'm talking about," Aizawa interrupts before Uraraka can finish.

Izuku blinks a few times, confused.

"W-what?" asks Shinsou.

Aizawa sighs, and finally relaxes his posture somewhat.

"I trust you all not to go looking for unnecessary trouble, and as long as you had your provisional licenses with you, there's no reason for me to scold you for apprehending a couple of low level thugs."

Izuku looks over at Todoroki, finding his own confusion mirrored on his friend's face.

"Then what exactly are you upset about, sensei?" Todoroki asks.

In answer, Aizawa turns a pointed glare on Izuku.

"Problem child...you have _no idea_ who your new friend is, do you?"

"My new....friend...?" Izuku asks, his mind blanking completely. "I don't...do...do you mean the little kid from the restaurant and his big brother? He's just a hero student visiting from abroad, isn't he?"

Aizawa doesn't say anything for a moment, his eyes instead searching Izuku's face for...something.

"Sawada Tsunayoshi," he finally says, holding Izuku's gaze, "Known in the criminal underground as Vongola Decimo, is the tenth generation head of Italy's most powerful mafia family, the Vongola."

"What the _fuck_!?" demands Katsuki, sitting up with wide eyes. "That puny little guy from the restaurant? He couldn't have been much older than us! What do you _mean_ he's a mafia boss?"

"Not yet," Aizawa corrects. "He's set to inherit his position next year in a formal ceremony that's set to be attended by some of the most powerful people in all of Italy, as well as a handful of notable people from Japan as well. I need you four to understand just how dangerous this man is. While the Japanese yakuza has been dwindling in power over the years due to the presence of All Might, the exact opposite has been happening in Italy. The mafia practically runs the country at this point, and it's all thanks to an alliance led by the Vongola."

"What is someone like _that_ doing in Japan?" asks Todoroki, inching closer to where Izuku is sitting as if to reassure himself that his friend really is right here next to him, whole and unharmed.

"That's what the police have been trying to find out," Aizawa answers.

"His littler brother said they were here visiting their mother," Izuku offers up, remembering what the kid had said to him while rambling. The child, at least, couldn't have been lying, right? Even if he was related to Sawada, someone that young shouldn't be able to deliver a lie so convincingly, right?

Aizawa inclines his head towards Izuku in acknowledgement.

"Unlikely," he says. "The child, Lambo Bovino, is not related to Sawada, and while it has been confirmed they visited Sawada Nana the day before, it is more likely that that is a cover story for why they're really in Japan."

"Why haven't they been arrested yet?" demands Katsuki. "How can someone like that be allowed to just walk around freely?"

Aizawa holds up three fingers. "One: he hasn't actually done anything illegal on Japanese soil so we don't have any authority to arrest him. Two: if we did try to arrest him without an ironclad reason, his family has enough money and lawyers to have him free in half a second. Three: not only is he ridiculously strong himself, he has a guard detail that would take no less than half of the top fifty heroes in Japan to take him down with minimal risk to civilians. It's simply not worth the risk to take him down if we don't have insurance that it will be for good and that he has no chance of getting off free."

Aizawa-sensei's body is still wound tight as a bowstring, and Izuku knows without a doubt that there's more he hasn't told them yet. He knows that at least part of Aizawa's anxiety comes from his students unknowingly being so close to someone so dangerous, but even that doesn't account for the way his leg bounces up and down anxiously, the way his knuckles are white with how hard he's clutching his crossed arms.

"W-well we got out of it without getting on his bad side, so everything is okay, right?" asks Uraraka. "We promise to not go back into town again for a while so we won't run the risk of seeing him again. You don't have to worry about us, sensei."

"I'm afraid that's not possible," Aizawa tells them through gritted teeth.

"What is that supposed to mean?" asks Todoroki.

Izuku has a sinking feeling he knows exactly where this conversation is headed when Aizawa turns to look at him with an apologetic expression on his face.

"The Hero Commission wants you to get close to him," says Aizawa.

"Absolutely fucking not!" Katsuki cuts in.

Aizawa doesn't even look in his direction.

Neither does Izuku, as he asks, "Why _me_?"

"You're the least threatening yet qualified candidate we have," says Aizawa. "I've been told about the interaction you had with them at the restaurant. Bovino seemed to have a good impression of you."

Izuku nods. "He's just...he's a normal little kid. He heard we were hero students and got excited. He said his big brother was one too."

This gets a disbelieving snort out of Aizawa.

"Well, as soon as the Hero Commission figured out you were a UA student, they started drafting up plans to have you get close to Sawada and figure out what his plans in Japan are. I tried to talk them out of it; you're still just a student for another year after all, you shouldn't have to take these kinds of risks..."

Izuku looks down when Aizawa pauses, already knowing his next words.

"They didn't listen to you," he finishes.

"I'm sorry, problem child," is his only reply.

Izuku takes a deep breath, taking a scant few moments to come to terms with his situation, before looking up with a brilliant smile on his face.

"You don't need to apologize, sensei!" he says. "Sawada is someone really dangerous, right? We can't let him just have his way in Japan. I'm happy to help apprehend someone as dangerous as him."

"Wait just a fucking second!" Katsuki snarls from next to them. "Don't any of us get a say in this!?" he demands, gesturing to Uraraka, Shinsou, and Todoroki, who are sat tense and unhappy, watching the scene with scowls on their faces.

Aizawa shakes his head jerkily. "Midoriya is the only one the Commision asked to-"

"Yeah, we got that part!" Uraraka interrupts. "But you can't just expect us to let our friend go into a dangerous mission like this alone!?"

"It's bad enough that Midoriya has to do this," says Aizawa. "I am _not_ going to let any of my other students get dragged into this mission if it can't be helped."

"But we can't let him do it _alone!"_ Shinsou interrupts.

"Of course he's not going to be alone," Aizawa barks, finally losing his patience. "He will have a team of capable pro heroes to back him up and make sure he remains as safe as possible throughout the mission. They are adults and have more training in this kinds of situations than any of you three."

"But-"

"Enough," Aizawa cuts off the protests immediately. "This is a top secret mission, be grateful the three of you were even brought into the loop. But don't you dare go around blabbing about it to the entire school. And that goes for the rest of you, too!"

The last sentence is spoken in the direction of the hallway leading to the stairs.

As soon as the words are spoken, there's the sound of shuffling, and then several pairs of footsteps running away from the dining room at top speed.

Aizawa sighs and shakes his head at his children's antics.

"You have your first mission briefing tomorrow morning," Aizawa tells Izuku. "Nedzu has assured me that there will be at least one of the UA teachers with you as an advisor for the mission, to make sure the Commission doesn't force you into anything beyond the scope of your abilities, so try not to stress too much, problem child."

Izuku smiles weakly.

"Thank you, sensei."

* * *

Tsuna relaxes back into his chair, lips pulled into a wide grin. 

"You really are a scary one, Reborn," he says to his teacher, who's sitting in a chair across from him.

The hitman shrugs, and meets Tsuna's grin with one of his own.

"Make sure you're paying attention, dame-Tsuna. These are the kinds of mind games you'll have to get used to playing if you're to have any kind of success as Decimo."

"Yeah, yeah, I know," says the young man, and the smile drops from his face as he looks down. "Pulling one over on the Hero Commission is always fun, no matter which country it's in, but I can't help but feel guilty about what we're putting Midoriya through. It's not gonna be pleasant."

"It could be worse," Reborn says dismissively. "Anyways, this is going to benefit him in the long-run too, you know. He needs to learn about these things early on, better to do it with us instead of anyone less savory. I think a little discomfort is worth what he'll get out of it in the end, don't you think?"

"I guess," Tsuna responds, though he still doesn't exactly look happy. "Just try not to be too hard on him, alright? And you better keep Mukuro and Hibari _far away_ from him, you hear? The poor guy does not deserve to have them inflicted on him."

**Notes for the Chapter:**

> Hey guys thank you so much for reading this chapter and I hope you enjoyed it! Please leave a comment down below letting me know what you thought!

**Author's Note:**

> Check me out on tumblr under the url skygemspeaks!


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